Background of the Invention
Field of the Invention
[0001] The present invention relates to rear wheel suspensions for bicycles. In particular
to such suspensions that mount the rear wheel on a swing arm so that, in response
to vibration and shocks, the wheel is able to move along a path relative to the bicycle
frame against counteracting forces applied to the swing arm by a shock absorbing mechanism.
Description of Related Art
[0002] Rear wheel suspensions for bicycles of the initially-mentioned type have been known
for over a century. While such suspensions have taken on numerous forms (see, e.g.,
British Patent No. 3982, German Patent No. DE 40 41 375, and U.S. Patent Nos. 392,523;
423,471; 463,710; 465,599; 2,756,071; 3,982,770; and 5,335,929), constant factors
have been the fact that wheel movement has been controlled to move in an arcuate path,
in most cases being dictated by the presence of a fixed, single (real or virtual)
pivot connection between the frame and the suspension to which the rear wheel is mounted,
and the fact that bicycles with these suspensions never were able to find more than
limited public acceptance.
[0003] The reasons why the prior rear wheel bicycle suspensions never attained wide public
acceptance, despite their ability, to a greater or lesser extent, to effectively absorb
shocks and vibrations, lie in the fact that they introduced other behavior characteristics
that were more disturbing than the shock and vibration problems they solved. That
is, unless the pedal crank pivot was mounted at or near the pivot connection of the
swing arm to the frame, the vertical component of the swing arm movement would adversely
impact on the pedaling "feel" and the rider's ability to effectively apply a constant
force to the pedals during riding. Furthermore, since the pedals, and therefore the
pedal crank pivot, must be located near the middle of the bicycle (underneath and
slightly forward of the seat), a bicycle with such a suspension produces a center
hinge effect which leads to several problems affecting riding comfort and performance.
In particular, a tendency exists for the front half (main frame) of the bicycle to
rock about the pivot connection between it and the swing arm. This rocking movement
changes the head angle and is perceived as a bobbing effect similar to riding a children's
"rocking horse". Moreover, the suspension can act to absorb a portion of the pedal
forces, affecting performance, and this absorption is translated into movement of
the suspension, again, affecting riding "feel". Similarly, application of braking
forces to the rear wheel would, in reverse, be transmitted into the suspension causing
the rider to experience a "sinking" effect. Existing systems have faced have faced
one or more other problems as well including traction and braking inconsistencies,
and handling inconsistencies under competition conditions, to name just a few.
[0004] With the advent of professional bicycle racing, not merely road or track racing,
but mountain or dirt bike racing, cross country and downhill (where bicycles travel
downhill over rough terrain at speeds of around 40 mph (67 km/h)), the demand for
high performance bicycle rear suspensions has increased, while the problems of prior
bicycle suspensions have been amplified under such racing conditions. That is, the
forces to which the suspension is subjected require increased wheel travel to absorb
the induced shocks as well as the need to use softer springs for bump compliance (i.e.,
so that the wheel will follow the bump instead of bouncing off it) for traction purposes.
However, changes of this type make previously "invisible" force problems not only
apparent, but unacceptable. Put another way, as wheel travel increases, the importance
of maintaining consistent (and constant) force functions within the bicycle-rider
system increases and this has been obtainable, to date, in most rear suspensions only
by the use of very stiff springs to correct for geometry induced problems (many suspensions
also limit downward wheel travel from static ride height to zero), thereby sacrificing
bump compliance.
[0005] In contrast to bicycles, motor vehicle, and particularly motorcycle, rear (drive)
wheel swing arm suspensions have been developed which do not use a single pivot motion
mechanism. For example, in US-A- 4,735,277, motorcycle drive wheel suspensions are
disclosed which use at least two swing arms, one of which is connected to the cycle
frame and a second of which is connected to the wheel, in a way which permits the
rear wheel to freely move in any direction relative to the frame within the plane
of rotation of the wheel and allowing the wheel to move along a plurality of paths.
However, considering that this patent contains no disclosure as to what purpose is
served by permitting the rear wheel to freely move in any direction relative to the
frame within the plane of rotation of the wheel and allowing the wheel to move along
a plurality of paths, and given the performance, applied load and ride differences
between motorcycles and bicycles, not to mention the presence of a frame-mounted motor
instead of a suspension-mounted pedal crank, no practical means or reason to apply
such a suspension to a bicycle can be derived from this patent.
[0006] Likewise, US-A- 4,671,525, discloses a suspension for the rear wheels of motor vehicles
in which the wheel-carrying swing arm forms part of a quadrilateral linkage assembly
in which the shock absorbing members can be located between any members and the geometry
of the articulated system can be designed to produce movement of the rear wheel along
any desired path, the described embodiment attaining an almost linear or slightly
curved path having a substantially vertical, upward and rearward inclination. However,
while the advantages of this suspension, in addition to being able to be adapted to
produce any desired path of movement, are indicated as including its ability to counteract
"sinking during an acceleration" and "raising when braked," due to its ability to
perform a long elastic excursion, no particular significance is attached to any particular
linkage configuration or resultant path of movement relative to this advantage or
any other. Thus, since this patent also relates to motor vehicle having a frame-mounted
motor instead of a suspension-mounted pedal crank, no practical means or reason can
be obtained from this patent to apply such a suspension to a bicycle, again, recognizing
the differences in performance, ride and applied forces occurring in the motorcycle
context in comparison to bicycles.
[0007] Thus, a need still exists for a rear wheel suspension for bicycles which will overcome
the above-mentioned problems associated with bicycle swing arm suspensions as they
have been constructed to date, and no means to fill that need from existing motorcycle
rear wheel suspensions being apparent. In particular, a need exists for a bicycle
rear wheel suspension which will meet the needs of competitive mountain bike racing.
[0008] From US-A-4,671,525 there is known a motorcycle rear wheel suspension of the pivoting
swing arm type with a swing arm having mounting means for connecting a motorcycle
rear wheel to a first end thereof, pivot means for pivotally connecting the swing
arm to a motorcycle frame near a second frame thereof, said suspension comprising
said pivot means being formed of a pair of upwardly converging links that are relatively
short in comparison to said swing arm, a first end of said converging links being
pivotally connected to the swing arm near a location at which a pedal crank is rotationally
mounted, and wherein said converging links and swing arm have a geometry forming a
means for producing a trajectory of rear wheel travel movement at the second end of
the swing arm which is a substantially vertically directed line path.
Summary of the Invention
[0009] In view of the foregoing, it is a primary object of the present invention to achieve
a swing arm type rear wheel suspension for a bicycle which will avoid the above-mentioned
problems associated with prior bicycle suspensions of this type.
[0010] In keeping with the foregoing object, a further object of the present invention is
to develop a high performance, swing arm type rear wheel suspension for a bicycle
having a multi-link swing arm assembly that is particularly adapted to the needs of
bicycles, especially mountain bikes for downhill racing, from such standpoints as
proper pedal crank location and "feel", wheel excursion path, traction and braking
performance, etc.
[0011] Still a further object of the present invention is to provide a rear wheel suspension
for a bicycle which can be attached to standard bicycle frames with minimal modifications.
[0012] These and other objects are achieved in accordance with the present invention as
defined in claims 1 and 12. In particular, a preferred embodiment of the invention
utilizes a three link suspension assembly that is formed of an essentially horizontal
swing arm which is pivotally attached at one end to the underside of the frame by
a pair of short links and which carries the rear wheel at an opposite end. The geometry
of the suspension assembly is designed to produce an essentially straight line trajectory
of the rear wheel in an upward and rearward direction at an angle that is preferably
20-30° with respect to a vertical line through the wheel axis of rotation to increase
traction, making the acceleration forces apply an upward vertical force component
to the frame independent of wheel position, and a downward force to the frame under
braking which helps to control the frame attitude. Furthermore, to obtain a constant
pedal "feel," the suspension geometry is also designed so that the maximum vertical
height movement of the pedal crank axis of rotation can be kept to less than 5% of
the vertical wheel travel (e.g., a .25" (63.5 cm) crank axis height increase for a
4" (10.16 cm) vertical wheel travel). The suspension is designed to attach to a frame
of a standard shape leaving room for mounting of the derailleur between the frame
and the rear wheel. In a particularly preferred form, the swing arm assembly is provided
with a tubular derailleur mount and an upper tube to which the rear wheel brake assembly
can be mounted.
[0013] These and other features of the invention are described below in greater detail with
respect to preferred embodiments of the invention and in conjunction with the accompanying
figures of the drawings.
Brief Description of the Drawings
[0014]
Figs. 1A & 1B are schematic depictions of a virtual single pivot swing arm as compared
to a real single pivot swing arm;
Figs. 2-4 are schematic force diagrams for purposes of describing the behavior of
conventional single pivot, swing arm rear wheel suspensions;
Fig. 5 is a diagrammatic depiction of the production of a straight line trajectory
for rear wheel travel via a three link swing arm assembly in accordance with the present
invention;
Figs. 6 and 7 are schematic diagrams of a first embodiment of the present invention;
Figs. 8-10 are schematic diagrams illustrating alternative suspension configurations
in accordance with the first embodiment of the present invention;
Fig. 11 shows a most preferred embodiment of the invention;
Fig. 12 shows an enlarged perspective view of a lateral stabilizing mechanism of the
Fig. 11 embodiment; and
Fig. 13 an alternative form for the lateral stabilizing mechanism;
Figs 14(A)-(C) show other relative positions for the converging links relative to
the crank of the suspension;
Figs. 15 & 16 show two forms for the pivot links and their connection to the swing
arm of the suspension; and
Fig. 17 shows a pivot link of the arrangement shown in Fig. 16.
Detailed Description of the Preferred Embodiments
[0015] In order to place the present invention in context, it is important to recognize
the source of problems associated with conventional single pivot swing arm bicycle
suspensions, whether the connection of the swing arm to the bicycle frame is achieved
via a real single pivot (Fig. 1A), e.g. a single swing arm
sa connected to a bicycle frame
F at a fixed location corresponding to pivot axis
P or via a virtual single pivot (Fig. 1B), i.e., a multi-link system in which the system
pivots the wheel axis
z about a pivot axis
P which is located at a point in space at which the center line of a pair of swing
arms sa converge. Likewise, it is important to point out certain basic constraints
within which the designer of a bicycle suspension must work to produce a suspension
that is usable with bicycle frames, pedal cranks, wheels, etc., which are conventionally
constructed.
[0016] Thus, initial reference is made to Fig. 2 in which a bicycle equipped with a single
pivot swing arm is diagrammatically depicted connected to a bicycle frame for rotation
about pivot axis
P. When the swing arm sa is horizontal, a line through the axes
P and
z is parallel to the ground, so that a drive force
F1 is applied to the frame and no vertical force component acts on the system at pivot
axis
P or on the wheel at axis
z. However, as the wheel moves up relative to the frame and axis
P through an angle Θ, the drive force
F1, e.g., when it hits a bump as represented in Fig. 3, an upwardly directed vertical
force component
F2 appears at wheel axis z and a downwardly directed vertical force component
F3 appears at pivot axis
P. These instantaneous forces at
P and
z are equal to
F1 sin Θ and is equal to half the driving force
F1 when Θ is 30°.
[0017] The significance of these vertical components is that when, as shown, the wheel axis
z is raised above the pivot axis
P, the vertical force component
F2 is directed upward and subtracts from the traction that the rear wheel can generate.
Furthermore, the vertical force component
F3 introduced at
P can cause the frame
F to move up or down. Additionally, for a given rear wheel travel, as the distance
between
P and
z is shortened, Θ increases and so do the vertical force components variations, traction
functions, attitude variations, etc. Clearly then, longer swing arms for a given wheel
travel is desirable since such will reduce force variations as a function of vertical
wheel position for any trajectory by reducing Θ toward zero. However, bicycle swing
arms are typically 13-24" (33.02 - 60.96 cm) long, the distance between the driving
sprocket and the driven sprocket (i.e., between axes
P and
z) is from 16.5-17.5" (41.91 - 44.45 cm) and the maximum permissible wheel travel set
at about 3-4" (7.62 - 10.16 cm) this being dictated by the minimum pedal-to-ground
clearance given a pedal crank axis mounting height of 12-13" (30.48 - 33.02 cm) and
an 8" (20.32 cm) distance from the pedal crank axis to the bottom of the pedal and
standard wheel diameters of 26-28" (66.04 - 71.12 cm). Thus, these constraints lead
to large Θ changes for all conventional single pivot rear wheel suspension swing arms,
and in turn, to traction and frame attitude variations.
[0018] Another factor of significance is braking. Not only are the independently actuated
brakes of a bicycle used to stop it, but under racing conditions the brakes are use
to control the height and attitude of the bicycle when entering corners (sometimes
the rear or front brake is used to "set" the bike's attitude while drifting, i.e.,
a two-wheel slide, into a corner). When the rear brake is applied, a retarding force
acts between the tires and the ground which the bicycle experiences as a force
FB that is directed rearward and parallel to the ground at wheel axis
z. The force
FB must be great enough to overcome the mass of the bicycle and its rider, which mass
is centered above the height of the front wheel axis. As a result, a significant moment
about axis
z is created that is proportional to the mass of the bicycle and rider, the height
of the mass center above the rear wheel axis
z, and the deceleration rate. With reference to Fig. 4, it can be seen that, for a
single pivot swing arm, this braking force
FB results in a downward force
F4 at axis
P and a like upward force
F5 at axis
z, which act to counteract the mass moment and which increase as the length of the
swing arm is decreased. As such, since it is these forces that are used to control
bicycle height and attitude, increasing the length of the swing arm to minimize problems
of traction and frame attitude variations during riding would counteract the ability
of the rider to use the brake caliper forces to enhance anti-lift.
[0019] In the above context, the nature and significance of the developments according to
the present invention will now be explained. As pointed out above, for a given wheel
travel, the longer the swing arm, the smaller the vertical force component imposed
on the bicycle which can affect wheel traction and frame attitude, yet in the bicycle
context constraints exist which severely limit the length which the swing arm can
be made. To overcome the limitation, the present invention utilizes the fact that
extremely long swing arms cause the wheel to travel along an arcuate trajectory that
approaches a straight line path. Thus, the present invention utilizes a three-link
swing arm assembly to produce a rear wheel trajectory which is essentially a straight
line so as to produce the effect of an essentially infinite length single pivot swing
arm.
[0020] However, as also described above, a long swing arm length will defeat the ability
of the rider to control bicycle height and attitude by the application of braking
forces. This problem is addressed in accordance with the present invention by making
the swing arm rotate and translate so as to produce a linear or slightly radiused
rear wheel trajectory in a manner which is not related to the apparent effective length
of the swing arm, so that the caliper can "think" it is mounted on a short swing arm
to produce the desired anti-lift function. This is achieved by pivotally connecting
the "long" swing arm to the frame via a pair of minimum length pivot links. In this
regard, Fig. 5 diagrammatically depicts how the swing arm sa can pivot as does a conventional
short swing arm, in conjunction with swinging of pivot links
L1 and
L2 yet the wheel axis
z can follow a straight line trajectory
T at a rearward angle Θ (preferably 20-30°) that is set to produce the desired braking
force anti-lift component and a vertical component
F2, in response to a forward driving force, that acts downward to increase traction
over bumps. In the case where the suspension of the present invention is to be applied
to a bicycle equipped with a front fork suspension, advantageously, the angle Θ is
matched to the angle of the trajectory of movement of the front wheel, such being
conventionally around 18-22°, since this can increase the dynamic stability of the
bicycle.
[0021] Specific embodiments for implementing the developments according to the present invention
will now be described. In this regard, it is noted that while only a single swing
arm assembly (swing arm and connecting links) is described below, it should be appreciated
that all embodiments of the present invention possess a pair of identical swing arms
SA at each of opposite lateral sides frame and rear wheel of the bicycle. These swing
arms may be connected to a common upright or may be separate, and in either case,
they are coupled to the frame
F by the pivot links
L1 and
L2, as described below and particularly as shown in Figs. 15-17.
[0022] Fig. 6 shows a bicycle 1 having a frame
F, a front wheel 3 that steerably connected to the frame
F, a rear wheel 5 that is driven by a pedal-operated chain drive assembly 7, all of
conventional design. Additionally, a rear wheel suspension 10 of the pivoting swing
arm type is provided which has a swing arm
SA having standard wheel axle mounting notches 9 for connecting the rear wheel 5 to
a first end thereof. A pedal crank
C of the chain drive assembly 7 is rotationally mounted on the swing arm
SA as is a mount BR for a brake caliper B.
[0023] For pivotally connecting the swing arm
SA to the frame
F of the bicycle near a second end thereof, a pair of upwardly converging links
L1,
L2 are provided that are relatively short in comparison to swing arm
SA, preferably, having a length that is no more than about 10% of the length of the
swing arm. A first end of the converging links
L1,
L2 are pivotally connected to the swing arm
SA at
P2,
P4 near a location at which pedal crank
C is rotationally mounted, and a second end thereof is connected to frame
F near a lower end thereof at
P1,
P3. Any form of known shock absorbing means (spring, elastomer, air, hydraulic or hybrid
combination thereof) can be connected between the bicycle frame and the suspension
at any location thereof; but, in accordance with the present invention, preferably,
the connection of a shock absorber 11 to the suspension 10 is provided by a pivotal
connection of the shock absorber 11 to an extension of one of the links
L1,
L2, such as at pivot point
P3 shown in Fig. 7, since this allows connection to a point which moves linearly with
respect to wheel travel and thereby enabling a linear spring rate curve to be achieved.
[0024] An import aspect of the invention is the providing the converging links
L1,
L2 and swing arm
SA with a geometry which produces a trajectory
T-T' of rear wheel travel movement at the second end of the swing arm which is a substantially
straight line path, preferably at an angle Θ of between 20-30° and which, at the same
time, restricts the maximum vertical movement of the pedal crank to within a range
of about 5% to 10% of rear wheel vertical travel based upon a percentage of about
5 % for a rear wheel vertical travel of about 4" (10.16 cm) and a percentage of about
10% for a rear wheel vertical travel of about 2" (5.08 cm), .i.e, the crank axis follows
a path
t-t' which produces a vertical height displacement of, e.g., .25" (63.50 cm) or less.
Various computer programs are available that can be used to determine suitable geometries
for the links and swing arm to produce these results are, given the above-mentioned
size constraints and the trajectory to be produced, or such can be determined empirically.
In this regard, solely by way of example, a swing arm
SA of 17" (43.18 cm) has proved suitable for use with links
L1 and
L2 of 1.44" (3.66 cm) and 2.3" (5.84 cm) respectively to achieve a substantially straight
line wheel travel of 4.0" (10.16 cm).
[0025] Figs. 8-10, by way of example only, show other possible configurations for link
L1 and placement of shock absorber 11, the arrangement of Fig. 9 offering the advantage
of leaving an area
xx free for placement of the derailleur of a standard gear shift mechanism. Likewise,
Figs. 14A-C show other relative positions for the converging links
L1,
L2 relative to the crank C. Changing of the link positions will affect their length,
but generally, the link
L1 will be always be about 60-70% of the length of
L2.
[0026] Figs. 11 and 12 show a most preferred embodiment of the present invention. In this
embodiment, the swing arm
SA is part of a triangular frame-shaped assembly 14 having an upright 15 positioned
near the location at which said pedal crank is rotationally mounted and a crosspiece
16 that extends between the upright 15 and the end of the swing arm
SA that is connected to the rear wheel 5. This complete assembly 14 attaches to the
bicycle frame
F by a single bracket 17 at a single interface surface, thereby limiting the modification
which must be made to frame
F to the provision of a mounting surface for bracket 17. A rear wheel brake mount
BR for a brake caliper is provided on crosspiece 16 and a mount 18 for the derailleur
of a gear shift mechanism is provided on the upright 15 of the frame-shaped assembly
14.
[0027] This triangular configuration of the assembly 14 provides increased structural rigidity.
Moreover, a lateral support means 20 can be carried by the upright 15. The lateral
support means 20 serves for restricting lateral deflection of assembly 14 in a manner
which will not affect the trajectory
T-T' of rear wheel travel movement produced by the geometry of converging links
L1,
L2 and swing arm
SA. In a first form, the lateral support means 20 comprises a pair of scissor links
L3,
L4 that are pivotally connected to each other, scissor link
L3 being pivotally connected to the seat post 22 of the bicycle frame
F and the scissor link
L4 being pivotally connecting to the upright 15. The scissor links
L3,
L4 can be very small, e.g., only 1" (2.54 cm) between pivot connections, since they
serve only for lateral stability and need only execute a very small vertical displacement
of the pivot point on upright 15. As such they do not constitute an appreciable added
weight.
[0028] An alternative form of lateral support means 20' comprises a fork-shaped bracket
25 connected to the top of upright 15. Bracket 25 has a pair of guide arms 26, 27
which slidingly straddles the seat post 22 of the bicycle frame
F.
[0029] As mentioned above, the two swing arms SA, whether separate or connected, are preferably
joined to the frame by a single pair of links
L1 and
L2. The reason for this is that use of a single pair of links (instead of to pairs of
links) enables the links
L1,
L2 to resist lateral loads and optimally also torsional deflections. In Fig. 15, solid
links
L1,
L2 are shown mounted on pins which extend between rigid plate-shaped extensions of the
assembly 14. In contrast, Fig. 16 shows an assembly 14 having a solid link-mounting
extension to which the H-shaped links
L1,
L2 shown in Fig. 17 mount. The H-shaped links
L1,
L2 shown in Fig. 17 are also suitable for use when separate swing arms
SA are used instead of the assembly 14.
[0030] While various embodiments in accordance with the present invention have been shown
and described, it is understood that the invention is not limited thereto, and is
susceptible to numerous changes and modifications as known to those skilled in the
art. Therefore, this invention is not limited to the details shown and described herein,
and includes all such changes and modifications as are encompassed by the scope of
the appended claims.
1. A bicycle rear wheel suspension of the pivoting swing arm type with a swing arm (SA)
having mounting means (9) for connecting a bicycle rear wheel (5) to a first end thereof,
pivot means for pivotally connecting the swing arm (SA) to a bicycle frame near a
second end thereof, a pedal crank (C) rotationally mounted on the swing arm (SA),
and shock absorbing means (11) for connection between the bicycle frame and the suspension;
characterized in that said suspension comprises said pivot means being formed of a
pair of upwardly converging links (L1, L2) that are relatively short in comparison to said swing arm (SA), a first end of said
converging links (L1, L2) being pivotally connected to the swing arm (SA) near a location at which said pedal
crank (C) is rotationally mounted; and wherein said converging links (L1, L2) and swing arm (SA) have a geometry forming a means for producing a trajectory of
rear wheel travel movement at the second end of the swing arm (SA) which is a substantially
straight line path and forming a means for restricting maximum vertical movement of
the pedal crank (C) to within a range of about 5% to 10% of rear wheel vertical travel
based upon a percentage of about 5 % for a rear wheel vertical travel of about 4"
(10.16 cm) and a percentage of about 10% for a rear wheel vertical travel of about
2" (5.08 cm).
2. A bicycle rear wheel suspension according to claim 1, wherein a rear wheel brake means
is mounted on the swing arm (SA).
3. A bicycle rear wheel suspension according to claim 1, wherein a mount for a gear shift
derailleur is provided on the swing arm (SA).
4. A bicycle rear wheel suspension according to claim 1, wherein said pivot links (L1, L2) have a length that is no more than about 10% of the length of the swing arm (SA).
5. A bicycle rear wheel suspension according to claim 1, wherein said swing arm (SA)
is part of a triangular frame-shaped assembly having an upright (15) positioned near
the location at which said pedal crank (C) is rotationally mounted; and wherein lateral
support means (20) is carried by said upright (15), said lateral support means having
means for restricting lateral deflection of said assembly without affecting the trajectory
of rear wheel travel movement produced by the geometry of said converging links (L1, L2) and swing arm (SA).
6. A bicycle rear wheel suspension according to claim 5, wherein said lateral support
means (20) comprises a pair of scissor links (L3, L4) pivotally connected to each other, one of said scissor links (L3, L4) being pivotally connected to said upright and the other of said scissor links having
means for pivotally connecting it to the bicycle frame.
7. A bicycle rear wheel suspension according to claim 5, wherein said lateral support
means (20) comprises a fork-shaped bracket (25) connected to said upright (15) and
having guide arms for slidingly straddling a vertical post of the bicycle frame.
8. A bicycle rear wheel suspension according to claim 5, wherein a rear wheel brake means
is mounted on a crosspiece of the frame-shaped assembly that extends between the upright
(15) and said second end of the swing arm (SA).
9. A bicycle rear wheel suspension according to claim 5, wherein a derailleur is mounted
on the upright (15) of the frame-shaped assembly.
10. A bicycle rear wheel suspension according to claim 1, wherein the shock absorbing
means (11) is connected to an extension of one of said pivot links.
11. A bicycle rear wheel suspension according to claim 1, wherein said trajectory of rear
wheel travel movement is inclined upwardly and rearwardly at an angle of 20-30° with
respect to a vertical line passing through the connection of the bicycle rear wheel
to the first end of the swing arm (SA).
12. A bicycle having a frame (F), a front wheel (3) steerably connected to the frame (F),
a driven rear wheel (5), and a rear wheel suspension of the pivoting swing arm type
with a swing arm (SA) having mounting means (9) connecting the rear whell (5) the
bicycle to a first end thereof, pivot means for pivotally connecting the swing arm
(SA) to the frame (F) of the bicycle near a second end thereof, a pedal crank (C)
rotationally mounted on the swing arm (SA), and shock absorbing means connected between
the bicycle frame (F) and the suspension; characterized in that said suspension comprises
said pivot means being formed of a pair of upwardly converging links (L1, L2) that are relatively short in comparison to said swing arm (SA), a first end of said
converging links (L1, L2) being pivotally connected to the swing arm (SA) near a location at which said pedal
crank (C) is rotationally mounted and a second end thereof being connected to said
frame (F); and wherein said converging links (L1, L2) and swing arm (SA) have a geometry forming a means for producing a trajectory of
rear wheel travel movement at the second end of the swing arm (SA) which is a substantially
straight line path and forming a means for restricting maximum vertical movement of
the pedal crank (C) to within a range of about 5% to 10% of rear wheel vertical travel
based upon a percentage of about 5% for a rear wheel vertical travel of about 4" (10.16
cm) and a percentage of about 10% for a rear wheel vertical travel of about 2" (5.08
cm).
13. A bicycle according to claim 1, wherein a rear wheel brake means is mounted on the
swing arm (SA).
14. A bicycle according to claim 12, wherein a derailleur is mounted on the swing arm
(SA).
15. A bicycle according to claim 12, wherein said pivot links (L1, L2) have a length that is no more than about 10% of the length of the swing arm (SA).
16. A bicycle according to claim 12, wherein said swing arm (SA) is part of a triangular
frame-shaped assembly having an upright (15) positioned near the location at which
said pedal crank is rotationally mounted; and wherein lateral support means (20) is
carried by said upright (15), said lateral support means having means for restricting
lateral deflection of said assembly without affecting the trajectory of rear wheel
travel movement produced by the geometry of said converging links (L1, L2) and swing arm (SA).
17. A bicycle according to claim 16, wherein said lateral support means (20) comprises
a pair of scissor links (L3, L4) pivotally connected to each other, one of said scissor links (L3, L4) being pivotally connected to said upright and the other of said scissor links being
pivotally connecting to the bicycle frame (F).
18. A bicycle according to claim 16, wherein said lateral support means comprises a bracket
(25) connected to said upright (15) and having guide arms slidingly straddling a vertical
post (22) of the bicycle frame (F).
19. A bicycle rear wheel suspension according to claim 5, wherein a rear wheel brake means
is mounted on a crosspiece of the frame-shaped assembly that extends between the upright
(15) and said second end of the swing arm (SA).
20. A bicycle rear wheel suspension according to claim 19, wherein a mounted for a derailleur
of a gear change mechanism is provided on the upright (15) of the frame-shaped assembly.
21. A bicycle rear wheel suspension according to claim 19, wherein the shock absorbing
means (11) is connected to an extension of one of said pivot links.
22. A bicycle rear wheel suspension according to claim 19, wherein said trajectory of
rear wheel travel movement is inclined upwardly and rearwardly at an angle of 20-30°
with respect to a vertical line passing through the connection of the bicycle rear
wheel (5) to the first end of the swing arm (SA).
1. Fahrrad-Hinterradaufhängung des Schwingarmtyps mit einem Schwingarm (SA), der Anbringungsmittel
(9) zur Verbindung eines Fahrradhinterrades (5) mit einem ersten Ende desselben aufweist,
Gelenkmitteln zum gelenkigen Verbinden des Schwingarms (SA) mit einem Fahrradrahmen
in der Nähe eines zweiten Ende desselben, einer drehbar an dem Schwingarm (SA) angebrachten
Pedalkurbel (C), und Stoßdämpfungsmitteln (11) zum Anschluß zwischen dem Fahrradrahmen
und der Aufhängung, dadurch gekennzeichnet, daß die Aufhängung die Gelenkmittel als
ein Paar von nach oben zusammenlaufenden Verbindungsgliedern (L1, L2) aufweist, die
im Vergleich zum Schwingarm (SA) verhältnismäßig kurz sind, wobei ein erstes Ende
der zusammenlaufenden Verbindungsglieder (L1, L2) gelenkig mit dem Schwingarm (SA)
in der Nähe einer Stelle verbunden ist, an welcher die Pedalkurbel (C) drehbar angebracht
ist, und wobei die zusammenlaufenden Verbindungsglieder (L1, L2) und der Schwingarm
(SA) eine Geometrie haben, welche Mittel zur Erzeugung einer Bewegungsbahn der Hin-
und Herbewegung des Hinterrads am zweiten Ende des Schwingarms (SA), welche im wesentlichen
eine Gerade ist, und welche Mittel zur Begrenzung der maximalen Vertikalbewegung der
Pedalkurbel (C) auf einen Bereich von etwa 5 % bis 10 % der Hinterrad-Vertikalbewegung,
beruhend auf einem Prozentsatz von etwa 5 % für eine Hinterrad-Vertikalbewegung von
etwa 4" (10,16 cm) und einem Prozentsatz von etwa 10 % für eine Hinterrad-Vertikalbewegung
von etwa 2" (5,08 cm), bilden.
2. Fahrrad-Hinterradaufhängung nach Anspruch 1, wobei Hinterradbremsmittel an dem Schwingarm
(SA) angebracht sind.
3. Fahrrad-Hinterradaufhängung nach Anspruch 1, wobei an dem Schwingarm (SA) eine Anbringung
für eine Kettenschaltung vorgesehen ist.
4. Fahrrad-Hinterradaufhängung nach Anspruch 1, wobei die Schwenkverbindungsglieder (L1,
L2) eine Länge haben, die 10 % der Länge des Schwingarms (SA) nicht übersteigt.
5. Fahrrad-Hinterradaufhängung nach Anspruch 1, wobei der Schwingarm (SA) Teil eines
dreiecksrahmenförmigen Aufbaus mit einer Stütze (15) ist, die in der Nähe der Stelle,
an der die Pedalkurbel (C) drehbar angebracht ist, angeordnet ist, und wobei auf der
Stütze (15) Seitenhaltmittel (20) sitzen, wobei die Seitenhaltmittel Haltemittel zur
Begrenzung einer seitlichen Ablenkung des Aufbaus ohne Beeinflussung der Bewegungsbahn
der durch die Geometrie der zusammenlaufenden Verbindungsglieder (L1, L2) und des
Schwingarms (SA) erzeugten Hinterradbewegung aufweisen.
6. Fahrrad-Hinterradaufhängung nach Anspruch 5, wobei die Seitenhaltmittel (20) ein Paar
von drehbar miteinander verbundenen Scherengliedern (L3, L4) aufweisen, wobei eines
der Scherenglieder (L3, L4) schwenkbar mit der Stütze verbunden ist und das andere
der Scherenglieder Mittel zur drehbaren Verbindung seiner selbst mit dem Fahrradrahmen
aufweist.
7. Fahrrad-Hinterradaufhängung nach Anspruch 5, wobei die Seitenhaltmittel (20) einen
gabelförmigen Bügel (25) aufweisen, der mit der Stütze verbunden ist und Führungsarme
zum gleitenden Übergreifen einer Vertikalstrebe des Fahrradrahmens aufweist.
8. Fahrrad-Hinterradaufhängung nach Anspruch 5, wobei die Hinterradbremsmittel auf einem
Querträger des rahmenförmigen Aufbaus angebracht sind, der sich zwischen der Stütze
(15) und dem zweiten Ende des Schwingarms (SA) erstreckt.
9. Fahrrad-Hinterradaufhängung nach Anspruch 5, wobei eine Kettenschaltung an der Stütze
(15) des rahmenförmigen Aufbaus angebracht ist.
10. Fahrrad-Hinterradaufhängung nach Anspruch 1, wobei die Stoßdämpfungsmittel (11) mit
einem Fortsatz eines der Gelenk-Verbindungsglieder verbunden sind.
11. Fahrrad-Hinterradaufhängung nach Anspruch 1, wobei die Bewegungsbahn der Hinterradlaufbewegung
unter einem Winkel von 20 bis 30° nach oben und nach hinten in bezug auf eine vertikale
Linie geneigt ist, die durch die Verbindung des Fahrradhinterrads mit dem ersten Ende
des Schwingarms (SA) verläuft.
12. Fahrrad mit einem Rahmen (F), einem lenkbar mit dem Rahmen (F) verbundenem Vorderrad
(3), einem angetriebenen Hinterrad (5) und einer Fahrrad-Hinterradaufhängung des Schwingarmtyps
mit einem Schwingarm (SA), der Anbringungsmittel (9) zur Verbindung eines Fahrradhinterrades
(5) mit einem ersten Ende desselben aufweist, Gelenkmitteln zum gelenkigen Verbinden
des Schwingarms (SA) mit einem Fahrradrahmen in der Nähe eines zweiten Ende desselben,
einer drehbar an dem Schwingarm (SA) angebrachten Pedalkurbel (C), und Stoßdämpfungsmitteln
(11) zum Anschluß zwischen dem Fahrradrahmen und der Aufhängung, dadurch gekennzeichnet,
daß die Aufhängung die Gelenkmittel als ein Paar von nach oben zusammenlaufenden Verbindungsgliedern
(L1, L2) aufweist, die im Vergleich zum Schwingarm (SA) verhältnismäßig kurz sind,
wobei ein erstes Ende der zusammenlaufenden Verbindungsglieder (L1, L2) gelenkig mit
dem Schwingarm (SA) in der Nähe einer Stelle verbunden ist, an welcher die Pedalkurbel
(C) drehbar angebracht ist, und wobei die zusammenlaufenden Verbindungsglieder (L1,
L2) und der Schwingarm (SA) eine Geometrie haben, welche Mittel zur Erzeugung einer
Bewegungsbahn der Hin- und Herbewegung des Hinterrads am zweiten Ende des Schwingarms
(SA), welche im wesentlichen eine Gerade ist, und welche Mittel zur Begrenzung der
maximalen Vertikalbewegung der Pedalkurbel (C) auf einen Bereich von etwa 5 % bis
10 % der Hinterrad-Vertikalbewegung, beruhend auf einem Prozentsatz von etwa 5 % für
eine Hinterrad-Vertikalbewegung von etwa 4" (10,16 cm) und einem Prozentsatz von etwa
10 % für eine Hinterrad-Vertikalbewegung von etwa 2" (5,08 cm), bilden.
13. Fahrrad nach Anspruch 12, wobei Hinterradbremsmittel an dem Schwingarm (SA) angebracht
sind.
14. Fahrrad nach Anspruch 12, wobei eine Kettenschaltung an dem Schwingarm (SA) angebracht
ist.
15. Fahrrad nach Anspruch 12, wobei die Schwenkverbindungsglieder (L1, L2) eine Länge
haben, die 10 % der Länge des Schwingarms (SA) nicht übersteigt.
16. Fahrrad nach Anspruch 12, wobei der Schwingarm (SA) Teil eines dreiecksrahmenförmigen
Aufbaus mit einer Stütze (15) ist, die in der Nähe der Stelle, an der die Pedalkurbel
(C) drehbar angebracht ist, angeordnet ist, und wobei auf der Stütze (15) Seitenhaltmittel
(20) sitzen, wobei die Seitenhaltmittel Haltemittel zur Begrenzung einer seitlichen
Ablenkung des Aufbaus ohne Beeinflussung der Bewegungsbahn der durch die Geometrie
der zusammenlaufenden Verbindungsglieder (L1, L2) und des Schwingarms (SA) erzeugten
Hinterradbewegung aufweisen.
17. Fahrrad nach Anspruch 16, wobei die Seitenhaltmittel (20) ein Paar von drehbar miteinander
verbundenen Scherengliedern (L3, L4) aufweisen, wobei eines der Scherenglieder (L3,
L4) schwenkbar mit der Stütze verbunden ist und das andere der Scherenglieder Mittel
zur drehbaren Verbindung seiner selbst mit dem Fahrradrahmen aufweist.
18. Fahrrad nach Anspruch 16, wobei die Seitenhaltmittel (20) einen gabelförmigen Bügel
(25) aufweisen, der mit der Stütze verbunden ist und Führungsarme zum gleitenden Übergreifen
einer Vertikalstrebe des Fahrradrahmens aufweist.
19. Fahrrad-Hinterradaufhängung nach Anspruch 5, wobei die Hinterradbremsmittel auf einem
Querträger des rahmenförmigen Aufbaus angebracht sind, der sich zwischen der Stütze
(15) und dem zweiten Ende des Schwingarms (SA) erstreckt.
20. Fahrrad-Hinterradaufhängung nach Anspruch 19, wobei eine Anbringung für eine Kettenumschaltung
eines Gangwechselmechanismus auf der Stütze (15) des rahmenförmigen Aufbaus vorgesehen
ist.
21. Fahrrad-Hinterradaufhängung nach Anspruch 19, wobei die Stoßdämpfungsmittel (11) mit
einem Fortsatz eines der Gelenk-Verbindungsglieder verbunden sind.
22. Fahrrad-Hinterradaufhängung nach Anspruch 19, wobei die Bewegungsbahn der Hinterradlaufbewegung
unter einem Winkel von 20 bis 30° nach oben und nach hinten in bezug auf eine vertikale
Linie geneigt ist, die durch die Verbindung des Hinterrads (5) des Fahrrads mit dem
ersten Ende des Schwingarms (SA) verläuft.
1. Suspension de roue arrière de bicyclette du type à bras oscillant pivotant munie d'un
bras oscillant (5A) ayant un dispositif de montage (9) destiné au raccordement à une
roue arrière (5) de bicyclette par une première extrémité du bras, un dispositif à
pivot destiné à raccorder de manière pivotante le bras oscillant (5A) à un cadre de
bicyclette près d'une seconde extrémité du bras, un pédalier (C) monté afin qu'il
puisse tourner sur le bras oscillant (5A), et un dispositif amortisseur (11) destiné
à être raccordé entre le cadre de bicyclette et la suspension, caractérisé en ce que
la suspension comprend le dispositif à pivot qui est formé d'une paire de bielles
(L1, L2) qui convergent vers le haut et qui sont relativement courtes par rapport au bras
oscillant (5A), une première extrémité des bielles convergentes (L1, L2) étant raccordée de manière pivotante au bras oscillant (5A) près d'un emplacement
auquel le pédalier (C) est monté afin qu'il tourne, et en ce que les bielles convergentes
(L1, L2) et le bras oscillant (5A) ont une configuration géométrique formant un dispositif
de production d'une trajectoire du mouvement de déplacement de la roue arrière, à
la seconde extrémité du bras oscillant (5A), qui est pratiquement un trajet rectiligne
et formant un dispositif destiné à limiter le déplacement vertical maximal du pédalier
(C) à une plage comprise entre environ 5 et 10 % de la course verticale de la roue
arrière, avec un pourcentage d'environ 5 % pour une course verticale de la roue arrière
d'environ 10,16 cm (4 pouces) et un pourcentage d'environ 10 % pour une course verticale
de la roue arrière d'environ 5,08 cm (2 pouces).
2. Suspension de roue arrière de bicyclette selon la revendication 1, dans laquelle un
dispositif de frein de roue arrière est monté sur le bras oscillant (5A).
3. Suspension de roue arrière de bicyclette selon la revendication 1, dans laquelle une
monture de dérailleur de changement de vitesse est placée sur le bras oscillant (5A).
4. Suspension de roue arrière de bicyclette selon la revendication 1, dans laquelle les
bielles pivotantes (L1, L2) ont une longueur qui ne dépasse pas 10 % environ de la longueur du bras oscillant
(5A).
5. Suspension de roue arrière de bicyclette selon la revendication 1, dans laquelle le
bras oscillant (5A) fait partie d'un ensemble en forme de cadre triangulaire ayant
un montant (15) placé près de l'emplacement auquel le pédalier (C) est monté afin
qu'il tourne, et dans laquelle un dispositif de support latéral (20) est supporté
par le montant (15), le dispositif de support latéral comprenant un dispositif destiné
à limiter le décalage latéral de l'ensemble sans affecter la trajectoire pendant le
mouvement de déplacement de la roue arrière produit par la configuration géométrique
des bielles convergentes (L1, L2) et du bras oscillant (5A).
6. Suspension de roue arrière de bicyclette selon la revendication 5, dans laquelle le
dispositif de support latéral (20) comporte deux bielles en ciseaux (L3, L4) raccordées de manière pivotante l'une à l'autre, l'une des bielles en ciseaux (L3, L4) étant raccordée de manière pivotante au montant et l'autre des bielles en ciseaux
ayant un dispositif de raccordement pivotant de cette bielle au cadre de la bicyclette.
7. Suspension de roue arrière de bicyclette selon la revendication 5, dans laquelle le
dispositif de support latéral (20) comporte une patte (25) en forme de fourche raccordée
au montant (15) et ayant des bras de guidage destinés à chevaucher de manière coulissante
une barre verticale du cadre de la bicyclette.
8. Suspension de roue arrière de bicyclette selon la revendication 5, dans laquelle un
dispositif de frein de roue arrière est monté sur une traverse de l'ensemble en forme
de cadre qui s'étend entre le montant (15) et la seconde extrémité du bras oscillant
(5A).
9. Suspension de roue arrière de bicyclette selon la revendication 5, dans laquelle un
dérailleur est monté sur le montant (15) de l'ensemble en forme de cadre.
10. Suspension de roue arrière de bicyclette selon la revendication 1, dans laquelle le
dispositif amortisseur (11) est raccordé à un prolongement de l'une des bielles de
pivot.
11. Suspension de roue arrière de bicyclette selon la revendication 1, dans laquelle la
trajectoire du mouvement de déplacement de la roue arrière est inclinée vers le haut
et vers l'arrière d'un angle compris entre 20 et 30° par rapport à une verticale passant
par le raccord de la roue arrière de la bicyclette à la première extrémité du bras
oscillant (5A).
12. Bicyclette possédant un cadre (F), une roue avant (3) raccordée au cadre (F) afin
qu'elle puisse être dirigée, une roue arrière menée (5), et une suspension de roue
arrière du type à bras oscillant pivotant possédant un bras oscillant (5A) comprenant
un dispositif de montage (9) raccordant la roue arrière (5) de la bicyclette à une
première extrémité du bras, un dispositif à pivot destiné à raccorder de manière pivotante
le bras oscillant (5A) au cadre (F) de la bicyclette près d'une seconde extrémité
du bras, un pédalier (C) monté afin qu'il puisse tourner sur le bras oscillant (5A)
, et un dispositif amortisseur raccordé entre le cadre de bicyclette (F) et la suspension,
caractérisée en ce que la suspension comprend le dispositif à pivot qui est formé
de deux bielles (L1, L2) qui convergent vers le haut et qui sont relativement courtes par rapport au bras
oscillant (5A), une première extrémité des bielles convergentes (L1, L2) étant raccordée de manière pivotante au bras oscillant (5A) près d'un emplacement
auquel le pédalier (C) est monté afin qu'il puisse tourner et une seconde extrémité
de la bielle étant raccordée au cadre (F) , et en ce que les bielles convergentes
(L1, L2) et le bras oscillant (5A) ont une configuration géométrique formant un dispositif
de production d'une trajectoire du mouvement de déplacement de la roue arrière, à
la seconde extrémité du bras oscillant (5A), qui est pratiquement un trajet rectiligne
et formant un dispositif destiné à limiter le déplacement vertical maximal du pédalier
(C) à une plage comprise entre environ 5 et 10 % de la course verticale de la roue
arrière, avec un pourcentage d'environ 5 % pour une course verticale de la roue arrière
d'environ 10,16 cm (4 pouces) et un pourcentage d'environ 10 % pour une course verticale
de la roue arrière d'environ 5,08 cm (2 pouces).
13. Bicyclette selon la revendication 1, dans laquelle un dispositif de frein de roue
arrière est monté sur le bras oscillant (5A).
14. Bicyclette selon la revendication 12, dans laquelle un dérailleur est monté sur le
bras oscillant (5A).
15. Bicyclette selon la revendication 12, dans laquelle les bielles pivotantes (L1, L2) ont une longueur qui ne dépasse pas 10 % environ de la longueur du bras oscillant
(5A).
16. Bicyclette selon la revendication 12, dans laquelle le bras oscillant (5A) fait partie
d'un ensemble en forme de cadre triangulaire ayant un montant (15) positionné près
de l'emplacement auquel le pédalier est monté afin qu'il tourne, et dans lequel un
dispositif de support latéral (20) est supporté par le montant (15), le dispositif
de support latéral comprenant un dispositif destiné à limiter le déplacement latéral
de l'ensemble sans affecter la trajectoire du déplacement de la roue arrière produit
par la configuration géométrique des bielles convergentes (L1, L2) et du bras oscillant (5A).
17. Bicyclette selon la revendication 16, dans laquelle le dispositif de support latéral
(20) comporte deux bielles en ciseaux (L3, L4) raccordées de manière pivotante l'une à l'autre, l'une des bielles en ciseaux (L3, L4) étant raccordée de manière pivotante au montant et l'autre des bielles en ciseaux
étant raccordée de manière pivotante au cadre (F) de la bicyclette.
18. Bicyclette selon la revendication 16, dans laquelle le dispositif de support latéral
comporte une patte (25) raccordée au montant (15) et ayant des bras de guidage chevauchant
de manière coulissante une barre verticale (22) du cadre (F) de la bicyclette.
19. Suspension de roue arrière de bicyclette selon la revendication 5, dans laquelle un
dispositif de frein de roue arrière est monté sur une traverse de l'ensemble en forme
de cadre qui s'étend entre le montant (15) et la seconde extrémité du bras oscillant
(5A).
20. Suspension de roue arrière de bicyclette selon la revendication 19, dans laquelle
une monture de dérailleur d'un mécanisme de changement de vitesse est placée sur le
montant (15) de l'ensemble en forme de cadre.
21. Suspension de roue arrière de bicyclette selon la revendication 19, dans laquelle
le dispositif amortisseur (11) est raccordé à un prolongement de l'une des bielles
pivotantes.
22. Suspension de roue arrière de bicyclette selon la revendication 19, dans laquelle
la trajectoire de déplacement de la roue arrière est inclinée vers le haut et vers
l'arrière d'un angle de 20 à 30° par rapport à une verticale passant par le raccord
de la roue arrière (5) de la bicyclette à l'extrémité avant du bras oscillant (5A).